# gcc-plugin-scallgraph

Small gcc compiler plugin to generate a function callgraph of the compiled source code and works with gcc-8.3 ... gcc-11.1  

This is a very small gcc compiler plugin to generate a function callgraph of the compiled sourcecode.

Because it is so small it should be easy to understand or customize to your own whishes.

To compile this it needs on debian Linux the package gcc-plugin-dev installed for the used gcc version.

To compile:  
./autogen.sh  
./configure  
make  

In directectory .libs ahould be a scallgraph_plugin.so.0.0.0 file created  

To use this plugin the path to the plugin so file must be specified like this  
gcc -c -fplugin=.libs/scallgraph_plugin.so test.c  

This generates a scallgraph.gv dot graph file with the callgraph of the routines.  

This dot file can be used with gml4gtk graph viewer or dot program.  

Other use:  
make CFLAGS="-fplugin=.libs/scallgraph_plugin.so"  

Or with own customized gcc compiler  
./configure CC=$HOME/mygcc/bin/gcc  

And indirect function calls are not in the graph  

This is tested and works with gcc-8 and gcc-11.1 on debian Linux 2021 see the rungcc.sh script  

Also:  
make clean  
make distclean  

This is example graph output in test.c.scallgraph.gv  

// function callgraph generated with gcc scallgraph plugin running with gcc version 11.1.0  
digraph scallgraph {  
 "f" -> "h";  
 "f" -> "g";  
 "g" -> "h";  
 "main" -> "f";  
}  
  

Now a better callgraph plugin for gcc will follow  

Other way to generate callgraph using gcc:  
gcc -fcallgraph-info text.c  

The generated *.ci file is a vcg graph file usable with gml4gtk graph viewer  

Or another way to generate callgraph is using the egypt script and generate gfcc rtl data  

The Linux kernel source has maintained gcc plugins in directory linux/scripts/gcc-plugins/  

Todo: to re-write based on the routines in gcc for -fcallgraph-info and add sfg.c to create callgraph images during compilation  
